Tagged: noise reduction

Airspy 2022 Summer Sale + SDR# Noise Reduction Improvements

Airspy is currently holding a 15% off summer promotion which runs until June 30. The sale is active at all participating resellers, which includes our own store where we have the YouLoop on sale for US$29.71 including free shipping to most countries in the world. Please note that due to new EU VAT collection laws, EU customers must purchase the discounted YouLoop from our eBay or Aliexpress stores. 

The YouLoop is a low cost passive loop antenna for HF and VHF. It is based on the Möbius loop design which results in a high degree of noise cancelling. However the main drawback is that it is a non-resonant design, which means that it works best when used with ultra sensitive receivers like the Airspy HF+ Discovery. 

Some good reviews include the YouTube videos done by Frugal Radio where he reviews HF reception and VLF & LF reception with an Airspy HF+, and later tests it with an RTL-SDR Blog V3 using direct sampling. Techminds also has an excellent review on his YouTube channel. We also have a product release overview on this post from March 2020.

Airspy SDR# Noise Reduction Improvements

We also wanted to highlight some recent improvements to SDR#, the official software for Airspy products, and compatible with the RTL-SDR. One recent development is the introduction of the Natural Intelligence Noise Reduction (NINR) feature which results less audio artifacts, deeper noise cancelling, and lower CPU usage.

Airspy "NINR" Noise Reduction on 40m

SDR# Noise Reduction Plugins Updated + SDR-Console Testing Deep Learning Noise Reduction

SDR# Noise Reduction Algorithms
SDR# Noise Reduction Algorithms

Recently the SDR# team have updated the algorithm on the noise reduction plugins used in SDR#. It appears that both the IF and Audio noise reduction plugins were updated with a better smoothing algorithm. We briefly tested the new algorithm and compared it against an older version. The new algorithm has noticeably less hiss and is slightly clearer when compared at the same noise reduction level. We tested with the same threshold levels and using the speech profile.

At the same time we've also seen news that Simon of SDR-Console is working on another noise reduction algorithm based on deep neural networks in the latest private beta version. A video of it in action was posted by Paul J in the SDRplay users group (note that you will need a Facebook account and will probably need to be a member of the SDRplay group to view that video). The algorithm seems to be based on the RNNoise paper that was posted here. The SDR# algorithm was also tweaked based on information gained from that paper although it doesn't use neural networks directly.

SDR# NR Comparison

Unprocessed Audio

Old SDR# NR Algorithm

New SDR# NR Algorithm

Digital Noise Reduction Plugin for SDRSharp

A new digital noise reduction plugin for SDRSharp has been released. It is packaged as part of the SDRSharp binaries. Head to the SDRSharp downloads page, and download and use the automated installer for rtl-sdr under the heading “Important note for RTL-SDR users”.

Then in SDRSharp, simply click “Enabled” in the Digital Noise Reduction plugin window and adjust the slider until you get good results. In testing I found significant improvements in noise reduction.

SDRSharp Noise Reduction Plugin